"By the time I got to NASA, I’d been around a block a bunch of times and been in some very difficult circumstances," said Jemison, the first black woman to travel into space.

The military trainers who took her through wilderness survival probably wish they had looked up that background.

"For some reason, they decided they wanted to pick on me, which I'm probably the worst person to pick on," she said. "I used to hunt with my dad. I'm a doctor. You can't gross me out. I've worked in Africa. I've worked with all kinds of diseases."

After killing a bird, they chose Jemison to clean it.

"I know that they thought I was going to be 'uhhh,'" she said. "I remember plucking (the bird) and they said, 'OK now you have to take the insides out,' and I said, 'They're already out' and I had them in my hand."

Jemison's classmates also displayed a wide range of expertise, with backgrounds as test pilots, neurologists and astrophysicists. "What was really exciting about it was there were so many things you had to learn," she said about astronaut training. "And then getting to learn a lot about the work that other folks did."

"It’s a big fire hydrant of information and that’s really exciting," said Jemison, who today leads the 100 Year Starship Project, a nonprofit initiative with the goal of ensuring the capabilities exist for human beings to travel to another star by 2112.

Mae Jemison(Photo: NASA)

The training was so comprehensive that actually going into space didn't phase Jemison, who also helped actors get into the mindset of an astronaut on National Geographic Channel's series "MARS."

"Of course it's different because what you can't train for is the consistent zero-g but you start to get used to it," she said. "The human body is remarkable for its resiliency."

Leland Melvin, another former NASA astronaut, had a similar experience. When he went into space for the first time, Melvin was in charge of robotics. His job centered around the installation of another module to the International Space Station.

"I'd never done that before. I'd only done it in the equivalent of a video game," he said. "All of our training is basically screens and hand controllers, just like a video game."

Mission Specialist Leland Melvin poses for a photo on the shuttle Atlantis. Drink and food packets float around him in 2009.(Photo: NASA)

"When it came to the day that you've got to show that you've got the right stuff ... I realized that the training was exactly like what I felt in space. The dynamics of the arm moved the same way that they did on the ground in this virtual space," Melvin said.

By the time he came to NASA, Melvin also carried an impressive list of accomplishments. As a NFL player, he was well versed in the mental discipline and physical aptitude needed to pass the rigorous tests. "Land survival, water survival – those weren't too difficult for me," he said.

The hardest – and what ended up being his favorite – part of training? Flying. "You're just holding off going Mach 1 because you would blow out all the windows," he said. "You're deploying these speed breaks to keep you below Mach so you can come in safely."

This close-up view of a water bubble floating freely on the space shuttle Atlantis shows a refracted image of astronaut Leland Melvin.(Photo: NASA)

Melvin enjoyed the aerobatics of rolls, loops and turns involved in flying, even when the pilot was trying to pull a multiple G-force turn. They're "trying to knock you unconscious," he said. "You're trying to force the blood to stay inside your head so that you don't pass out."

As for how long training takes to complete? That's an open-ended question. Melvin first traveled into space in 2007, nine years after he entered the astronaut training program in 1998.

Even when astronauts go into orbit more quickly, the training never stops, Jemison said.

"You're always training," she said. "Even when you come back from a mission you're still training."